<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<style>#internal { background: yellow; }</style>
<link rel="stylesheet" href="external.css">
<style>
blockquote::after { content: attr(style); }
</style>
</head>
<body>
<blockquote id="internal">internal background: yellow;</blockquote>

<blockquote id="external">external background: yellow;</blockquote>
</body>
</html>
